Actually, parritae cannot take heat well at all -- maybe for several days, but the prolonged summer heat of the deep South will quickly kill it. It's a Tacsonia-type Passiflora, none of which can handle prolonged periods of temps in the 90s F.
Mark (zostropz) sold some this year, and you may also want to check http://www.strangewonderfulthings.com. Strybing arboretum sells some at their plant sales, but that's in San Francisco. My impression is that it's relatively easier to obtain if you live in the San Fran area, but even then it's difficult to come by. It is said to be very difficult to propagate by cuttings, and getting the plants to set seed is hard, since there is only one clone in the US, and it is not readily self-compatible. The best information that I've come by is that parritae is NOT extinct in the wild; rather, it is still known to grow natively in at least a couple places in South America.
If you're in Florida, you'll likely need a special cooled greenhouse to grow it.
I've watched the Grassy Knoll site pretty closely for over a year now, but I've never seen parritae for sale there -- are you sure that's the plant you bought from Elizabeth at Grassy Knoll? If so, did you have to special request it from her?
I know you grow a lot of Passiflora, but I'm still suspicious that your plant is not a parritae. I'm in North Carolina, and even though our summers are a touch cooler than in southern Florida, I know from experience that Tacsonias die pretty quickly in the heat, having lost many of them myself (my other Passiflora, on the other hand, flourish in the heat). Did you grow the plant indoors? Or in deep shade? No Tacsonia of mine has ever survived a summer outdoors here.
Might you have a picture of the plant? Even the leaves of parritae are pretty distinctive, and that may put my skepticism to rest. If you indeed succeeded in growing parritae in Florida, then your technique is quite enviable.